Yep. I know a guy, born and raised in Massachusetts, who's a Giants fan. When he grew up being a Pats fan was like being a fan of the local minor affiliate of a big team. So his team is the next closest one that was actually important.

The Steelers. They were really bad until the 70s and the infusion of $3 million from the AFL/NFL merger. The reason the Steelers are in the AFC and not the NFC is because of that payout that probably saved the franchise.